1. Field of the Invention
The present invention relates to a valve, and more particularly, to a bi-stable ball valve that uses an electromagnet actuation.
2. Description of the Related Art
Valves are connected to a tube to control the flow rate or pressure of a fluid. One type of valve is the ball valve, which is an essential element of a microfluidic system, such as a fluid transportation system for a fluid control system through a fluid channel, a fluid switch for a reagent sample, and sample intake, calibration, and rinsing of a reagent.
FIG. 1 is a cross-sectional view illustrating a conventional ball valve that uses an electromagnet (refer to O. Krusemark, A. Feustel, and J. Muller, μ (micro) TAS'98, pp. 399-402, 1998).
Referring to FIG. 1, the conventional ball valve comprises a channel part 110, a ball 120, a cover unit 130 above the channel unit 110, and an electromagnet 140 above the cover unit 130. The channel unit 110 includes a fluid outlet 112 and a taper type valve seat 114. The cover unit 130 includes a fluid inlet connected to a long radius area of the valve seat 114. The electromagnet 140 applies a magnetic force to the ball 120.
When a current is applied to the electromagnet 140 from an external power source (not shown), the electromagnet produces a magnetic field. When the ball 120 is lifted toward the cover unit 130 by the magnetic field, the valve is kept open.
However, in the conventional valve having the above structure, energy is continuously consumed when the valve is open, since the ball drops when the current supply is disconnected.
Also, the above valve is kept closed by the fluid pressure, but when the fluid pressure is not sufficient, the valve may leak.